To make the leek mashed potatoes, place the potatoes in a saucepan and pour over boiling water to cover by 5 cm. Bring back to a boil, then reduce the heat and cook for 15–20 minutes or until the potatoes are very tender.

Meanwhile, spread out the crushed peppercorns on a plate and press the steaks into them until they are coated with peppercorns on all sides. Set aside.

Heat the oil for the mashed potatoes in a nonstick frying pan. Add the leeks and cook, stirring constantly, for 3–5 minutes or until tender. Transfer to a plate lined with a double thickness of paper towel to drain. Heat the milk in a saucepan until hot.

When the potatoes are tender, drain them, shaking the colander or sieve to remove any excess water, and return them to the pan. Pour the hot milk over the potatoes, then mash them until they are completely smooth. Add the leeks, mustard and margarine, and season with pepper. Beat well to mix, then cover and keep warm.

Heat a ridged cast-iron broil pan over a high heat until hot. Brush the pan with the olive oil, then reduce the heat to medium-high. Place the steaks in the pan and cook for 3 minutes on each side for rare, 3 1/2 minutes on each side for medium-rare, 4 minutes on each side for medium, or 5 minutes on each side for well done.

Spoon a mound of potatoes on each warmed plate and place a pepper steak next to it. Drizzle any pan juices over the steaks and sprinkle with parsley or chives. Serve immediately.

Recipe Notes

Pepper steak with leek mashed potatoes variations: Veal loin chops can be cooked in the same way. Use 4 chops, 2 cm thick and about 250 g each. (This weight includes the bone; it should give about 150 g meat.) Brush the chops with oil and season with pepper to taste, omitting the peppercorns. Cook as for the steaks, allowing 3 minutes on each side for medium-rare; 3 1⁄2 minutes on each side for medium; or 4 1⁄2 minutes on each side for well done.

Adding leeks to mashed potatoes not only boosts their flavour but also adds thiamine, vitamin B6 and folate. If you include the green part of the leeks this will also provide beta carotene. Eaten regularly, leeks are believed to help reduce the risk of heart disease and stroke.